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If batteries could be charged from the friction of scrolling, our phones would never die.(r/Showerthoughts)
I think you vastly overestimate the amount of energy generated thru friction. Even if you harnessed all of it, the charge would be negligible.
A better idea would be to capture the energy from jostling/shaking your phone. It’s still small, but they do make flashlights that work this way: www.amazon.com/Forever-Light-Shake-Flashlight/dp/B…